Lydia Ko, (left) and Stacy Lewis size up their putts on the 3rd hole, during the third round of the Swinging Skirts LPGA classic at Lake Merced Golf Club in Daly City, Calif., on Friday April 25, 2014.

They played in the same group Thursday and Friday. They played together again Saturday and put on an electric show on the back nine of Lake Merced Golf Club.

Stacy Lewis and Lydia Ko will tee off in the last group for Sunday's final round of the Swinging Skirts LPGA Classic. If Sunday's drama matches Saturday's theater, "Classic" will become an appropriate description.

Lewis is at 10-under-par 206 for three rounds, good for a one-shot lead over Ko. Each fired a 4-under 68 on Saturday; Lewis' round was bogey-free.

After three days together, Lewis joked that she and Ko might be "running out of things to talk about."

Lewis, 29, quickly complimented Ko, who turned 17 on Thursday.

"I love to play with her," Lewis said. "She doesn't take much time. We both kind of play fast. We got into a good rhythm there going back and forth."

Said Ko: "It's just really good for me as a rookie to play with a player like Stacy. It's a great opportunity for me to learn from another great player."

Ranked third in the world, Lewis churned out pars for the first 11 holes Saturday. Ko, No. 4 in the world, made birdies on the par-4 fifth and par-5 sixth to grab a one-stroke lead over Lewis.

Ko's lone bogey of the day came at No. 11, dropping her into a tie for first with Lewis. Then came a highly entertaining bout of "Anything you can do ..."

Each woman birdied No. 12, a par-3, to get to 7-under.

Ko chipped in for birdie at the par-3 15th. Moments later, Lewis drained a birdie putt and both players were at 8-under.

"It was really fun watching Stacy play," Ko said. "It kind of made me feel like I needed to play better."

Lewis said she and Ko fed off each other.

"I think it's made both of us kind of elevate our game," Lewis said. "It's a hard golf course, yet we're still making some birdies on it."

The birdie binge continued at the par-4 16th. Lewis coaxed home a putt from somewhere near the Daly City BART Station. She estimated the putt was a mere 45 feet. Sure enough, Ko stayed even with Lewis by jarring another putt.

Two years ago, Ko became the youngest winner in LPGA history when she won the Canadian Open as a 15-year-old amateur. Lewis played with Ko in that final round.

"I was impressed then," Lewis said. "I think the best part of her game is ... the maturity. Playing away from pins and not going after every pin. She is fearless out there on a couple of them, though.

"She definitely doesn't play like she's 17."

Golf Channel cameras captured Ko's father, G.H., reacting exuberantly as Lydia charged on the back nine. Dad caddied for daughter in last week's tournament in Hawaii in which she finished tied for 32nd.

"Last week, I was missing a lot of putts," Ko said, "so when he sees them going in this week, he's kind of surprised, and I guess the emotions are going."

Jenny Shin is in third place at 6-under after her second 68 in three rounds. She will join Lewis and Ko in the final group. Hee Young Park also shot a 68 and is in fourth, a stroke behind Shin.

Shin, Park or someone else could challenge Lewis and Ko on Sunday. That's one reason Lewis said she cannot afford to think of Sunday's round as simply a match-play duel with Ko.

"The golf course is so hard," Lewis said, "you can make a bogey really quick if you're just playing the person next to you.

"I think we're both going to probably stick to our game plans and (it's) going to be close coming down to the end. Hopefully, it's the good golf we saw today. I'm sure it'll be a lot of fun."